The present invention relates to a process for preparing printing sleeves supporting photopolymer plates for use as printing forms in printing techniques such as, for example, flexography or dry offset. The invention also relates to a device for implementing the process.
It is already known that it is possible to obtain a block for flexography by exposing a photopolymer plate sensitive to ultraviolet radiation, with the interposition of a negative film which leaves exposed to the radiation those zones which are to come into relief on the finished block.
Over the last few years, printing techniques have developed more and more towards increased use of printing sleeves or cylinders.
This is largely due to the latest technologies, which now make it possible to impress plates or photopolymer blocks directly by laser, with the laser moving along a horizontal axis parallel to the axis of rotation of the printing sleeve and with the printing sleeve rotating about its axis.
In the remainder of this description, the term printing sleeve will be used to define a photopolymer plate or block mounted on a printing cylinder.
There are currently machines and processes on the market which allow manual development of printing sleeves mounted on an expansible cylinder.
Each printing phase requires the use of a different printing sleeve which then entails time-consuming and tedious operations for preparing these sleeves. Moreover, such operations are most often carried out manually.
Devices which use printing sleeves are therefore expensive to employ in terms of manufacturing, and are also not entirely satisfactory in terms of results, because of the difficulties mentioned above, namely their manual and tedious nature.
It is therefore the primary object of the present invention to fully automate the entire process of preparing printing sleeves.
Another object of the present invention is to prepare printing sleeves in any format in a fully automatic machine which is hermetically sealed against any solvent vapor.
Many problems needed to be solved in order to achieve these objects. In particular, it was necessary to obtain an in-line machine taking up a minimal floor space, to provide an assembly which is fully sealed hermetically against solvent vapors, and to mount the sleeves on a transport spindle in the various development phases, for printing sleeves of arbitrary diameter and length.